The Tissue EM Core performs high-quality preservation of HIV-infected tissues from both humanized mouse model systems and actual human tissues from biopsies and explants. These samples are plastic-embedded, serially sectioned and imaged for tomographic analysis in either of two electron microscopes. Tomographic reconstructions provide three-dimensional, high-resolution studies of wild-type HIV within actual infected tissues and organs and may shed light on the fine structures involved in HIV budding and evasion from HAART therapy. The Core has most equipment necessary for processing, imaging and analyzing tissue samples. The core has effectively unlimited access to two tomography-ready electron microscopes: A FEI Tecnai T12 (120KeV) microscope for sections <200nm in the Caltech Broad Center EM Suite (see EM Tomography Core, Grant Jensen Director) and a newly retrofitted Tecnai TF30-FEG (300KeV) microscope for 300-400nm sections located in the Caltech Material Sciences Department.